I agree with what you're saying about stun guns, and granted you shouldn't have refreshed that many times , but as ftp myself, I use crystals for refreshing nodes when farming toons in hard nodes... people saying you should never refresh, either pay for shards or would unlock B1 in 2022.
In my case, I am over 1 month and counting without finding Stun Guns in Cantina store. I used to get them there occasionally, but now they're nowhere to be found in Cantina. If I'm lucky I'd get 5 stuns from Shard shop, guild events, and raids depending on rng.
Guildmates confirmed they noticed the same thing (though some were getting them at a much lower rate), so I sent a complaint to EA customer care with this issue to confirm whether stun drop rates in cantina have been modified, and this is the first line from the reply I got:
"Thank you for contacting EA help. My name is (*****) and I would assist you with your issue today in The Simpsons: Tapped Out."
Yep...
He then said they'll message me with a resolution, and that was 2 weeks ago.